Stabilization of motor fuels



Patented Sept. 10, 1935 UNITED STATES STABILIZATION OF MOTOR FUELSFrederick Baxter Downing, Carneys Point, N. J., and Herbert WarrenWalker, Wilmington, Del., assignors to E. I. du Pont de Nemours &Company, Wilmington, Del., a corporation of Delaware No Drawing.Application February 4, 1933, Serial No. 655,256

16 Claims. This invention relates to the stabilization of motor fuelsand more particularly to stabilization of cracked gasolines and thelike.

Motor fuels, particularly gasolines as ordinarily produced, arecomplicated mixtures comprising many constituents. Some of theseconstituents comprise unsaturated and aromatic hydrocarbons and othercompounds which normally tend to form gummy, resinous, insoluble ornon-volatile products upon storage and/or exposure to light, heat andthe atmosphere. This is particularly true of cracked gasolines. However,straightrun gasolines often contain substituents of this type. Also,unsaturated hydrocarbons are often added to straight-run gasolines.These gummy, resinous, insoluble and non-volatile products are highlyobjectionable in motor fuels. The formation of these objectionableproducts, together with their disadvantages, is well recognized by thoseskilled in the art and many expedients have been resorted to to obviatethe difliculties introduced thereby.

It has been proposed to treat such motor fuels with substances such assulfuric acid, fullers earth and the like to remove these gum formingconstituents. Such treatment has not proved to be satisfactory for thereason that the anti-knock value of a motor fuel so treated isappreciably lowered.

It has also been proposed to add various substances to motor fuels ofthis type to prevent the formation of these gummy products. The compounds added to motor fuels for this purpose are generally designatedgum inhibitors. The gum inhibitors heretofore employed have not provedto be entirely satisfactory as some of them tend to discolor the motorfuel and some of them are readily removed by water when the motor "fuelis brought into contact with water. Such contact with water causes lossof inhibitor and reduction in the stability of the motor fuel. It hasbeen found to be almost impossible to keep motor fuel permanently out ofcontact with water, in commercial practice.

An object of the present invention is to provide new gum inhibitors formotor fuels. A further object is to provide gum inhibitors which areinsoluble in water and have no tendency to discolor the motor fuel inwhich they are incorporated. Still further objects are to provide motorfuels and particularly cracked gasolines which do not tend to form gumon storage or on subjection to the action of light, heat and theatmosphere, which motor fuels are cheaper to manufacture and have ahigher anti-knock value. Other objects are to provide new compositionsof matter and to advance the art. Still other objects will appearhereinafter.

These objects may be accomplished in accordance withour invention whichcomprises incorporating in motor fuels, particularly cracked gasolinesand the like, a 2:3:4r5 tetra alkyl-l-hydroxy benzene or a 2:3:5:6 tetraalkyl-l-hydroxy benzene which compounds have the following respectiveformul'ze:

on on -A A -A A A A -A in which A represents an alkyl group. Among thecompounds which we have found to be particularly satisfactory for ourpurposes are the following:

2:3:425-tetramethyl-l-hydroxy benzene (J lls213:5:5-lctmetllyl-l-hydroxy benzene 3:5-dimethyl-2:G-diethyl-l-hydroxybenzene H502 C2Hs porated therein a small amount of the gum inhibitor at100 C. in an atmosphere of oxygen for a period of from 3 to 5 hours. Thegum formed is measured by evaporating the motor fuel, after the oxygentest, from a porcelain dish in a steam oven. The extent of gum formationduring the accelerated oxygen test is a measure of the stability andgumming tendency of the fuel during long time storage.

In order to more fully illustrate our invention and the advantageousresults to be obtained thereby the following example is given:

Emample 1 A freshly distilled cracked gasoline containing 0.005% of2:3:4z5-tetra methyl-l-hydroxy-benzene for each 25 cc. of the gasolinewas subjected to the accelerated oxygen test for 3% hours. The amount ofgum formed for each 25 cc. was 23 mg. An equal portion of the samegasoline containing no inhibitor, subjected to the same test at the sametime, gave 171 mg. of gum for each 25 cc. of the gasoline.

The concentration of the inhibitor required to produce a givenstabilizing effect will vary widely with the nature and concentration ofthe unsaturated constituents of the motor fuel and will generally varyin proportion with the molecular weight of the inhibitor. In general,however, the amount of inhibitor required will be substantially lessthan 0.1% of the motor fuel by weight.

The gum inhibitors of our invention have many advantages over thoseheretofore employed as they possess a greater degree of effectivenessthan any heretofore known. They have no tendency to discolor the motorfuel and are insoluble in water.

This application is a continuation in part of our co-pending application472,187, filed July 31, 1930, now Patent 1,945,521.

While we have specifically disclosed the preferred compounds containingonly methyl and ethyl groups, alkyl groups containing longer carbonchains such as the propyl and butyl groups may be employed, if desired.Other compounds will be readily apparent to those skilled in the 7 artwithout departing from the spirit of our invention. Accordingly, ourinvention is to be limited solely by the appended claims construed asbroadly as is permissible in view of the prior art.

We claim:

1. Motor fuel comprising cracked hydrocarbon spirits normally tending toform gum having incorporated therein, in an amount sulficient to inhibitthe formation of gum, a member of the group consisting of 2:3:4=:5-tetra-alkyl-1-hydroxy and 2:3:5:6-tetra-alkyl-1-hydroxy benzenes.I

2. Motor fuel comprising cracked hydrocarbon spirits normally tending toform gum having incorporated therein, in an amount sufficient to inhibitthe formation of gum, 2 3 5 G-tetra-methyll-hydro'xy benzene.

3. Motor fuel comprising cracked hydrocarbon spirits normally tending toform gum having incorporated therein, in an amount sufficient to'inhibitthe formation of gum, 223:4:5-tetraalkyl-l-hydroxy benzene.

4. Motor fuel comprising cracked hydrocarbon spirits normally tending toform gum having incorporated therein, in an amount sufficient to inhibitthe formation of gum, 2:3:4:5-tetramethyl-l-hydroxy benzene. 5

5. Cracked gasoline normally tending to form gum having incorporatedtherein, in an amount notexceeding about 0.1%, a member of the groupconsisting of 2:3:4:5-tetra-alkyl-l-hydroxy and2:3:5:6-tetra-alkyl-l-hydroxy benzenes to ma- 10 terially reduce theformation of gum by said cracked gasoline.

6. Cracked gasoline normally tending to form gum having incorporatedtherein, in an amount sufficient to inhibit the formation of gum,2:3:5:6- I5 tetra-methyll-hydroxy benzene.

'7. Cracked gasoline normally tending toform gum having incorporatedtherein, in anamount sufficient to inhibit the formation of gum, a2:3:4:5-tetra-alkyl-1-hydroxy benzene. 20

8. Cracked gasoline normally tending to form gum having incorporatedtherein, in an amount sufficient to inhibit the formation of gum, 2:3:4:5- tetra-methyl-l-hydroxy benzene.

9. The process of stabilizing cracked gasoline 25 which normally tendsto deteriorate on storage which process comprises adding to the gasoline2:3:5:6-tetra-methyl-l-hydroxy benzene in an amount sumcient to inhibitsuch deterioration.

10. The process of stabilizing cracked gasoline 30 which normally tendsto deteriorate on storage which process comprises adding to the gasolinea 2:3:4:S-tetra-alkyl-l-hydroxy benzene in an amount sufficient toinhibit such deterioration.

11. The process of stabilizing cracked gasoline 35 which normally tendsto deteriorate on storage which process comprises adding to the gasoline2:3:4:S-tetra-methyl-l-hydroxy benzene in an amount sufiicient toinhibit such deterioration.

12. Motor benzol normally tending to form 9 gum having incorporatedtherein, in an amount not exceeding 0.1% to inhibit the formation ofgum, a member of the group consisting of 2:3:4z5-

tetra-alkyl-l-hydroxy and 2 3 5 6-tetra-alkyl-1- hydroxy benzenes.

13. Motor benzol normally tending to form gum having incorporatedtherein, in an amount sufficient to inhibit the formation of gum,2:3:5z6- tetra-methyll-hydroxy benzene.

14. Motor benzol normally tending to form gum 50 having incorporatedtherein, in an amount suflicient to inhibit the formation of gum, a2:3:4:5- tetra-alkyl-l-hydroxy benzene.

15. Motor benzol normally tending to form gum' having incorporatedtherein, in an amount sufiicient to inhibit the formation of gum,2:3:4z5- tetra-methyl-l-hydroxy benzene.

16. The process of preserving cracked hydrocarbon distillates whichnormally tend to deteriorate on storage and develop gum which com- 0prises incorporating therein a member of the group consisting of2:3:415-tetra-a1kyl-1-hydroxy and 2:3:5:6-tetra-alkyl-1-hydroxy benzenesin amounts not exceeding about 0.1% to inhibit such deterioration andgum formation.

FREDERICK BAXTER DOWNING. HERBERT WARREN WALIER.

